Brushless Direct Current Motor End Cap

ABSTRACT

An end cap for a brushless motor that dissipates heat from a controller and switching elements of the motor through fins in the end cap. The end cap can be directly or thermally coupled to the controller and switching elements to dissipate heat out through the fins.

TECHNICAL FIELD OF THE INVENTION

The present application relates generally to end caps. Moreparticularly, the present application relates to brushless directcurrent motor end caps with heat dissipation structures.

BACKGROUND OF THE INVENTION

Brushless motors are a common electromechanical system used in everydayapplications. Some brushless motors operate by having a controller senda current signal through coils located on a stationary part called astator. The coils cause a magnetic force to be applied when current runsthrough the coils. The brushless motor also includes a rotating partcalled a rotor with magnets that interact with the magnetic forcescaused by the windings of the stator. A controller sends current throughthe coils on the stator, causing the magnetic field and the interactionbetween the stator magnetic field and the magnets on the rotor. Bysending a current signal through several coil windings in a particularorder, the stator creates a rotating magnetic field which interacts withthe rotor causing it to rotate and generate torque.

Brushless motors are especially prevalent in tools, such as drills andpower tools. The motors are activated by a trigger on a handle of thetool and apply torque to a working end of the tool. Many of these motorsare framed motors, which help prevent the motor from being damaged whenthe tool is dropped on the ground. Other motors are frameless, whichallow the rotor and stator to shift or twist with respect to one anotherwhen dropped on the ground. Framed motors are therefore helpful fordamage prevention, but require end caps to maintain structuralstability.

Brushless motors include controllers that include switching elements,such as metal oxide semiconductor field effect transistors (MOSFETs)that switch on and off the current signal sent through the coils of themotor. However, the effectiveness of the controller, its MOSFETs, andthe brushless motor are limited by the heat they generate. Therefore,these heat generating components require significant cooling to operateeffectively, which in power tools, is typically accomplished by airflowfrom the motor's fan. Some power tools place the controller and MOSFETsin the handle of the tool due to space limitations, cost, simplicity,etc. However, this provides a less compact design and makes cooling thecontroller more difficult because the airflow created by the fan isoften obstructed.

SUMMARY OF THE INVENTION

The present invention broadly comprises an end cap for a brushless motorthat acts as a heat sink and dissipates heat from a controller andMOSFETs of the motor. The end cap can include fins to dissipate heat andcan be directly or thermally coupled to the controller or MOSFETs todissipate heat out through the end cap. In this manner, the end capprovides a heat dissipation component with a compact design.

In particular, the present invention comprises a tool including a motorincluding a controller and switching elements. The controller controlsthe switching elements to operate the motor in response to a user input.An end cap is coupled to the motor, and includes an end cap base and afin coupled to the end cap base. The switching elements are thermallycoupled to the end cap.

Further disclosed is a motor comprising a controller that controls arotation of the motor, and switching elements electrically coupled tothe controller. The controller is adapted to control the switchingelements to switch on and off in response to a user input. An end cap iscoupled to the motor, and includes an end cap base and a fin coupled tothe end cap base. The switching elements are thermally coupled to theend cap.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the subject mattersought to be protected, there are illustrated in the accompanyingdrawings embodiments thereof, from an inspection of which, whenconsidered in connection with the following description, the subjectmatter sought to be protected, its construction and operation, and manyof its advantages should be readily understood and appreciated.

FIG. 1 is a side view of a tool according to at least one embodiment ofthe present invention.

FIG. 2 is a front perspective view of internal components of a toolaccording to at least one embodiment of the present invention.

FIG. 3 is a front view of an end cap according to at least oneembodiment of the present invention.

FIG. 4 is a partial side perspective sectional view of an end capaccording to at least one embodiment of the present invention, as takenalong line 4, 4 in FIG. 3.

FIG. 5 is a side sectional view of an end cap according to at least oneembodiment of the present invention, as taken along line 5, 5 in FIG. 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings, and will herein be described indetail, a preferred embodiment of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to embodiments illustrated. As used herein, theterm “present invention” is not intended to limit the scope of theclaimed invention and is instead a term used to discuss exemplaryembodiments of the invention for explanatory purposes only.

The present invention broadly comprises an end cap for a brushless motorthat dissipates heat from the controller and MOSFETs associated with themotor. The end cap can be directly or thermally coupled to thecontroller and MOSFETs to dissipate heat out through fins in the endcap.

FIG. 1 illustrates a tool 100 according to at least some embodiments ofthe present invention. As shown, the tool 100 includes a body 105leading to a handle 110, where the handle 110 has a trigger 112 forselectively allowing the flow of power from a power source 114 such as abattery or a direct wall socket connection. The trigger 112 thereforecauses a motor 115 to rotate and provide torque to a working end 117such as a drill bit or driver bit. An end cap 120 can be located on therear end of the motor 115 for structural and heat dissipation purposes,discussed below in more detail.

The body 105 can be any size or shape and generally includes at leastsome of the internal components necessary for the tool 100 to function.For example, the body 105 can house gear trains or electrical componentsthat cause torque to be applied to the working end 117.

The handle 110 can be ergonomically sized and shaped to be held by ahand of a user. The trigger 112 can be positioned at an upper portion ofthe handle 110 where the user's finger will likely be located duringuse. The handle 110 can be free of a controller or switching elements(such as MOSFETs) that would control the motor that drives the tool 100.

The motor 115 can be a direct current brushless motor, but the presentinvention is not so limited. The motor 115 can accordingly be anyelectromagnetic or electromechanical motor without deviating from thespirit and scope of the present invention.

As shown in FIGS. 2-5, the end cap 120 can serve as a structuralcomponent to help the motor 115 stay in position during, for example, adrop of the tool. The end cap 120 can also serve as a heat sink bydissipating heat from the end of the end cap 120 (rear, front, orotherwise) to the outside of the tool 100. For example, the end cap 120can be directly or thermally coupled to the controller and switchingelements (such as MOSFETs) that drive and control the motor 115 so as todissipate heat quickly from the components of the motor 115 (such ascontroller 130 and switching elements 135, described in further detailbelow) most affected by heat. The end cap 120 can be located on therear, front, top, bottom, or side of the tool; or any other location ofthe tool 100.

As shown in FIG. 2, the motor 115 can include an a shaft or axle 125that rotates and delivers torque to a gear train or other component,which eventually transfers the torque to the working end 117. The axle125 is coupled to the motor 115 and acts as the output of the motor 115when the motor 115 is activated.

The motor 115 can include a controller 130 coupled to switching elements135 (such as MOSFETs and/or other types of switching elements). Thecontroller 130 is adapted to control the switching elements 135 tooperate the motor 115 in response to a user input (such as actuation ordepression of the trigger 112). As shown and as understood in the art,the controller 130 causes the switching elements 135 to selectivelyswitch on and off various coils within the motor 115 so as to cause amagnetic interaction between the stator and rotor of the motor 115 andthereby drive the motor 115 and cause torque to be outputted via theaxle 125. The switching elements 135 (such as MOSFETs) may be arrangedin an H-bridge, for example, or in any other manner capable of operatingthe motor 115.

As shown in FIGS. 3-5, the end cap 120 can include an end cap base andan end cap ring 140 within a central portion of the end cap 120, one ormore fins 145 extending axially from the end cap 120, and one or moreslots 146 between adjacent ones of the fins 145. The end cap ring 140can be located in an axial center of the end cap 120 and define an endcap opening. The end cap ring 140 and end cap opening receive thebearing and shaft 125 of the motor 115, and allow the shaft 125 toextend through the end cap opening. The slots 146 allow air to flow intothe motor 115 for proper ventilation and the fins 145 help dissipateheat from the motor 115. As shown in FIG. 3, the end cap 120 can furtherinclude connection portions 150 to allow a fastener to couple the endcap to the body 105 or the remainder of the tool 100. In someembodiments, the fastener couples the end cap 120 to the stator of themotor 115.

The fins 145 can be conventional fins used with heat sink structures todissipate heat. The fins 145 can also be any other structure thatincreases the surface area of the end cap 120 and therefore allows thedissipation of heat from the controller 130 and switching elements 135.For example, the fins 145 can be curved or angled structures, orotherwise be shaped and sized to dissipate heat from the end cap 120. Inan embodiment, the switching elements 135 can be directly coupled to theend cap 120 at the fins 145, as shown.

As shown in, for example, FIG. 5, the end cap 120 is coupled directly tothe switching elements 135 which are coupled directly to the controller130. In this manner, the end cap 120 can dissipate heat more directlyand with better efficacy than structures that include other materialbetween the end cap 120 and the switching elements 135. In otherembodiments, the end cap 120 is thermally coupled to the switchingelements and controller 130, meaning the end cap 120 is coupled to theswitching elements and controller 130 via structure that is intended toconduct heat.

As used herein, the term “coupled” and its functional equivalents arenot intended to necessarily be limited to direct, mechanical coupling oftwo or more components. Instead, the term “coupled” and its functionalequivalents are intended to mean any direct or indirect mechanical,electrical, or chemical connection between two or more objects,features, work pieces, and/or environmental matter. “Coupled” is alsointended to mean, in some examples, one object being integral withanother object.

The matter set forth in the foregoing description and accompanyingdrawings is offered by way of illustration only and not as a limitation.While particular embodiments have been shown and described, it will beapparent to those skilled in the art that changes and modifications maybe made without departing from the broader aspects of the inventors'contribution. The actual scope of the protection sought is intended tobe defined in the following claims when viewed in their properperspective based on the prior art.

What is claimed is:
 1. A tool comprising: a motor including a controllerand switching elements, the controller controlling the switchingelements to operate the motor in response to a user input; an end capcoupled to the motor, the end cap comprising: an end cap base; and a fincoupled to the end cap base, wherein the switching elements arethermally coupled to the end cap.
 2. The tool of claim 1, wherein thecontroller is directly coupled to the switching elements and wherein theswitching elements are directly coupled to the end cap.
 3. The tool ofclaim 2, wherein the switching elements are directly coupled to the endcap at the fins.
 4. The tool of claim 1, wherein the fins extend axiallyfrom the end cap.
 5. The tool of claim 1, wherein the motor includes anaxle adapted to output torque generated by the motor.
 6. The tool ofclaim 1, wherein the end cap includes connection portions for couplingthe end cap to a portion of the tool.
 7. The tool of claim 1, whereinthe end cap includes an end cap ring located in an axial center of theend cap and defining an end cap opening.
 8. The tool of claim 1, whereinthe end cap includes a slot and the slot allows air to flow through theslot.
 9. A motor comprising: a controller that controls a rotation ofthe motor; switching elements electrically coupled to the controller,the controller adapted to control the switching elements to switch onand off in response to a user input; an end cap coupled to the motor,the end cap comprising: an end cap base; and a fin coupled to the endcap base, wherein the switching elements are thermally coupled to theend cap.
 10. The motor of claim 9, wherein the controller is directlycoupled to the switching elements and wherein the switching elements aredirectly coupled to the end cap.
 11. The motor of claim 10, wherein theswitching elements are directly coupled to the end cap at the fins. 12.The motor of claim 9, wherein the fins extend axially from the end cap.13. The motor of claim 9, wherein the motor includes an axle adapted tooutput torque generated by the motor.
 14. The motor of claim 9, whereinthe end cap includes connection portions for coupling the end cap to aportion of the tool.
 15. The motor of claim 9, wherein the end capincludes an end cap ring located in an axial center of the end cap anddefining an end cap opening.
 16. The motor of claim 9, wherein the endcap includes a slot and the slot allows air to flow through the slot.